On July 22, London's Guardian headlined "US military intervention in Syria would create 'unintended consequences.' "

On Monday, US Joint Chiefs Chairman General Martin Dempsey warned senators. He expressed concerns about greater escalation. Direct US involvement's risky, he said.

Once getting more heavily involved, it's hard to pull back, he stressed.

"We have learned from the past 10 years, however, that it is not enough to simply alter the balance of military power without careful consideration of what is necessary in order to preserve a functioning state," he explained.

"We must anticipate and be prepared for the unintended consequences of our action."

Each option considered entails costly uncertainties, he stressed. Arming and training opposition fighters is least risky. He estimates about "$500 million per year initially."

Doing so requires "several hundred to several thousand troops."

Limited air strikes entail "hundreds of aircraft, ships, submarines, and other enablers."

Costs will run "in the billions." At best, efforts will achieve little more than "significant degradation of regime capabilities and an increase in regime desertions." Assad can withstand the strikes, he said.

He estimates over $1 billion a month in cost. Implementation "may also fail to reduce the violence or shift the momentum because (Assad) relies overwhelmingly on surface fires - mortars, artillery, and missiles."

Even limited no-fly zone protection costs over $1 billion a month. It entails having "thousands of US ground forces" to maintain it.

Controlling Syria's chemical weapons requires "thousands of special operations forces and other ground forces would be needed to assault and secure critical sites."

To implement all of the above, some Pentagon sources believe about 70,000 US troops are needed. It's a substantial costly commitment. There's no assurance of success.

The entire effort may backfire. Syria's already a cauldron of violence and instability. It spilling cross-borders. It may affect the entire region and beyond.

Maybe a provocative false flag's planned. It wouldn't be the first time. Full-scale intervention may follow. It won't surprise. It's been likely for months. Only its timing is uncertain.

Daniel Byman is senior fellow and research director for Brookings' pro-Israeli Saban Center for Middle East Policy. Formerly he was Rand Corporation Center for Middle East Public Policy research director.

On July 22, he headlined "Go Big or Go Home," saying:

America's light regional footprint doesn't cut it. If Washington wants "to secure its interests, ranging from oil security to nuclear nonproliferation - (it) must once again play a leading role in the region."

"The end result isâ€¦the worst of all worldsâ€¦If the United States wants to protect its interests in the Middle East, it cannot rely on allies to do its bidding - or otherwise do so on the cheap."

"The United States must pay to playâ€¦The problems of the region are getting worse, and if the United States doesn't shore up its influence now, it will be even less relevant when it most needs to act."

Bynam suggests direct US intervention. So does Center for Strategic and International Studies analyst Anthony Cordesman.

On July 22, he headlined "Syria's ripple effect," saying:

"â€¦Syria continues to spiral out of control, affecting the security of Lebanon, Turkey, Iran and Iraq and giving Iran new opportunities."

America's losing. Assad's winning. If he "succeeds in crushing the opposition or otherwise maintains control over most of Syria, Iran will have a massive new degree of influence over Iraq, Syria and Lebanon in a polarized Middle East divided between Sunni and Shiite."

"Minorities will be steadily driven into exile. This would present serious risks for Israel, weaken Jordan and Turkey and, most important, give Iran far more influence in the Persian Gulf, an area home to 48 percent of the world's proven oil reserves."

"US officials could make clear that either 'rebels' will succeed" in ousting Assad "or the United States will join with allies in creating a no-fly zone."